1. Field of the Invention
The present invention relates to catalysts for the catalytic cracking of heavy oil. More particularly, it relates to catalysts for use in catalytic cracking of heavy oil, comprising crystalline aluminosilicate zeolites prepared by treating with an acidic solution containing iron ions.
2. Description of the Prior Art
Silica-alumina compounds have been widely used as catalysts for fluid catalytic cracking. Particularly, in recent years, the use of catalysts comprising silica-alumina or alumina blended with zeolite has increased because of their high cracking activity and durability. The catalysts have the disadvantage that they produce a gasoline fraction having only a low octane value, although they exhibit high cracking activity in catalytic cracking of heavy oil. Furthermore, an intermediate fraction including kerosene and light oil cannot be obtained in a sufficiently high yield. The recent oil situation has resulted in the intermediate fraction being in short supply. It has been desired to develop new catalysts, particularly catalysts which produce the intermediate fraction in a high yield.